Security paper

Abstract

Security paper adapted to resist fraudulent alteration of toner-printed information thereon and to make such alteration or attempts at alteration evident has a maximum Scott-Bond strength of 150 J m −2 ; a Bendtsen roughness of not more than about 150 ml min −1 ; and is size press or otherwise treated with a thermally-softenable polymer composition, for example acrylic polymer or copolymer, a polyvinyl acetate polymer, a vinyl acetate/ethylene copolymer, or a vinyl acetate/vinyl chloride/ethylene terpolymer. Preferably the paper has filler content of about 15% to about 20% by weight.

1. A paper adapted to receive toner-printed information thereon, wherein said paper:
 (a) has a maximum Scott-Bond strength of 150 J m −2 ; 
 (b) has a Bendtsen roughness of not more than about 150 ml min −1 ; and 
 (c) has been size pressed or otherwise treated with a thermally-softenable polymer composition, 
 so that said paper is a security paper adapted to resist fraudulent alteration of toner-printed information thereon and to make such alteration or attempts at alteration evident, 
 wherein internal cohesion of the paper is lower than inherent toner adhesion so that attempts to remove toner from the paper result in visually evident disruption of cellulose fibers in the paper. 
 
     
     
       2. Security paper as claimed in  claim 1 , wherein the Scott Bond strength of the paper is not more than 140 J m −2 . 
     
     
       3. Security paper as claimed in  claim 2 , wherein the paper has a filler content of about 15 to 20% by weight. 
     
     
       4. Security paper as claimed in  claim 3 , wherein the paper has a Bendtsen roughness value in the range 60 to 100 ml min −1 . 
     
     
       5. Security paper as claimed in  claim 2 , wherein the paper has a Bendtsen roughness value in the range 60 to 100 ml min −1 . 
     
     
       6. Security paper as claimed in  claim 1 , wherein the paper has a filler content of about 15 to 20% by weight. 
     
     
       7. Security paper as claimed in  claim 6 , wherein the paper has a Bendtsen roughness value in the range 60 to 100 ml min −1 . 
     
     
       8. Security paper as claimed in  claim 3 , wherein the paper has a filler content of at least about 15.4%. 
     
     
       9. Security paper as claimed in  claim 6 , wherein the paper has a filler content of at least about 17.8%. 
     
     
       10. Security paper as claimed in  claim 6 , wherein the paper has a filler content of at least about 18.4%. 
     
     
       11. Security paper as claimed in  claim 1 , wherein the paper has a Bendtsen roughness value in the range 60 to 100 ml min −1 . 
     
     
       12. Security paper as claimed in  claim 1 , wherein the thermally softenable polymer composition is derived form a latex or a colloidal dispersion. 
     
     
       13. Security paper as claimed in  claim 12 , wherein the thermally softenable polymer is incorporated in a starch surface sizing composition. 
     
     
       14. Security paper as claimed in  claim 1 , wherein the thermally softenable polymer composition comprises an acrylic polymer or copolymer, a polyvinyl acetate polymer, a vinyl acetate/ethylene copolymer, or a vinyl acetate/vinyl chloride/ethylene terpolymer. 
     
     
       15. Security paper as claimed in  claim 14 , wherein the thermally softenable polymer is incorporated in a starch surface sizing composition. 
     
     
       16. Security paper as claimed in  claim 1 , wherein the thermally softenable polymer composition comprises a styrene-acrylic copolymer. 
     
     
       17. Security paper as claimed in  claim 16 , wherein the thermally softenable polymer is incorporated in a starch surface sizing composition. 
     
     
       18. Security paper as claimed in  claim 17 , wherein the ratio of starch:styrene-acrylic copolymer is from 95:5 to 85:15 on a dry weight basis. 
     
     
       19. Security paper as claimed in  claim 18 , wherein the starch:styrene-acrylic copolymer mixture is present in an amount of about 5-6% on a dry basis, based on total dry weight of paper. 
     
     
       20. Security paper as claimed in  claim 19 , wherein the final dry paper has a basis weight of about 95 gm −2  and a starch:styrene-acrylic copolymer mixture coatweight of about 2-2.5 gm −2  per side. 
     
     
       21. Security paper as claimed in  claim 18 , wherein the ratio of starch:styrene-acrylic copolymer is about 90:10, on a dry weight basis. 
     
     
       22. A security document comprising a security paper as claimed in  claim 1 . 
     
     
       23. Security paper as claimed in  claim 1 , comprising a security feature. 
     
     
       24. Security paper as claimed in  claim 1 , wherein internal cohesion of the paper is lower than inherent toner adhesion so that attempts to remove toner from the paper result in visually evident disruption of cellulose fibers in the paper. 
     
     
       25. Security paper as claimed in  claim 24 , wherein the paper has a filler content of about 15 to 20% by weight. 
     
     
       26. Alteration resistant and tamper evident security document comprising a toner-printed information carried on a security paper according to  claim 1 . 
     
     
       27. Security document as claimed in  claim 26 , which is a bank cheque. 
     
     
       28. Security paper as claimed in  claim 1 , wherein the Scott Bond strength of the paper is not more than 130 J m −2 . 
     
     
       29. Security paper as claimed in  claim 1 , wherein the paper is a bank cheque paper which meets U.K. Clearing Bank Specification No. 1. 
     
     
       30. A method of producing a security document for the purpose of making toner-printed information subsequently applied to the security document more resistant to fraudulent alteration and of making such alteration or attempts at alteration evident, comprising:
 providing a paper which 
 (a) has a maximum Scott-Bond strength of 150 J m −2 ; 
 (b) has a Bendtsen roughness of not more than about 150 ml min −1 ; and 
 (c) has been size pressed or otherwise treated with a thermally-softenable polymer composition, 
 such that said paper is a security paper adapted to resist fraudulent alteration of toner-printed information thereon and to make such alteration or attempts at alteration evident, and 
 forming a security document comprising said security paper. 
 
     
     
       31. Method as claimed in  claim 30 , wherein the paper is a bank cheque paper which meets U.K. Clearing Bank Specification No. 1.